Japan began an aggressive policy of imperialism in the late 19th and early 20th centuries because Japan 1. needed raw materials for its factories. By the end of the 19th century, Japan had been opened up to Western markets in the form of US trade across the Pacific, which set the nation on a course of industrialization; however, the Japanese mainland lacks a vast majority of valuable industrial materials like coal and rubber. For a period of time, the Japanese were able to maintain industrialization via trade with rubber and coal producing countries. However, as the global depression set in and after former trade partners cut routes at the onset of war in Europe, the Japanese began to expand across Eastern Asia to secure materials.
